Various prior arts have been developed in connection with a sheet material bending system that includes a press brake, a tool stocker to detachably store a plurality of upper and lower tools, and a tool changing apparatus (an automatic tool changer (ATC)) to automatically change tools between the press brake and the tool stocker. A sheet material bending system according to one related art arranges a tool stocker on the left or right side of a press brake and employs a tool changing apparatus to change a tool with another. Another related art arranges a tool stocker on one side of or in front of a press brake and employs, for example, an industrial robot as a tool changing apparatus to change a tool with another.
These related arts need an increased area for the system as a whole. To save space, a sheet material bending system according to another related art arranges a tool stocker and a tool changing apparatus behind upper and lower tables and between left and right side frames of a press brake. Patent literatures disclosing the related arts are, for example, Japanese Unexamined Patent Application Publications No. S52-156164 (Patent Literature 1), No. H05-84520 (Patent Literature 2), No. H07-275941 (Patent Literature 3), and No. 2003-136144 (Patent Literature 4) and Published PCT International Application No. WO00/41824 (Patent Literature 5).